Which of the following is a physical property of copper?

• A. Copper has a reddish-brown color.
• B. Copper reacts with hydrochloric acid to produce hydrogen gas.
• C. Copper can be oxidized to form CuO.
• D. Copper forms a green patina when exposed to air.

Answer: (A)

Verified step by step guidance

1. Understand the difference between physical and chemical properties: Physical properties can be observed or measured without changing the substance's identity, while chemical properties describe how a substance reacts to form new substances.
2. Review each option and determine if it involves a change in the substance's chemical identity or just a physical characteristic.
3. For the option 'Copper has a reddish-brown color,' recognize that color is a physical property because it does not involve a chemical change.
4. For the options involving reactions with hydrochloric acid, oxidation to form CuO, and formation of a green patina, identify these as chemical properties because they involve chemical changes and new substances being formed.
5. Conclude that the physical property of copper among the options is its reddish-brown color, as it describes an observable characteristic without altering the substance chemically.